The present invention relates generally to the electrokinetic mass transfer of substances into and/or extracting substances from tissue and particularly to apparatus and methods for extracting, containing and/or delivering substance, e.g., a medicament to a treatment site.
Electrokinetic delivery of medicaments for applying medication locally through an individual's skin is known. One type of electrokinetic delivery mechanism is iontophoresis, i.e., the application of an electric field to the skin to enhance the skin's permeability and to deliver various ionic agents, e.g., ions of soluble salts or other drugs. In certain situations, iontophoretic transdermal or transmucocutaneous delivery techniques have obviated the need for hypodermic injection for many medicaments, thereby eliminating the concomitant problem of trauma, pain and risk of infection to the individual. Other types of electrokinetic delivery mechanisms include electroosmosis, electroporation, electromigration, electrophoresis and endosmose, any or all of which are generally known as electrotransport, electromolecular transport or iontophoretic methods. The electrokinetic delivery mechanism may also be accompanied by ultrasonic vibration to further facilitate electrokinetic transport of the substance, e.g., by opening pores in the skin. Ultrasound may be employed in a number of ways such as (i) traditional piezoelectric elements, (ii) Application Specific Integrated Circuits (ASIC) with ultrasound transmitter built in or (iii) by thin foil sheets with incorporated piezoelectric dipole elements.
There are several difficulties with electrokinetic delivery of substances such as medicaments. One is the heretofore need for somewhat cumbersome, bulky and costly equipment which oftentimes requires the presence of an individual at a doctor's office or treatment center and use of medical professionals to administer the medicament. Private, self-administration of medicaments or for diagnostic application by the individual at non-medical or non-professional facilities is highly desirable. Also, an easily transportable apparatus for electrokinetic delivery of medication, for example, a lightweight, compact portable device useful with an applicator packaged as a single or unit dosage applicator, appears ideal as a patient/consumer friendly self-administration system appropriate for many circumstances.